Communication method and communication system

ABSTRACT

Each of relay nodes  5   1  to  5   M  adds a no-disturbance notification information or a code error notification monitoring information to a received signal so as to transmit it. When a code error  7 E occurs in a section between a relay nodes  5   i−1  and 5 i , the relay node  5   i−1  transmits a signal  2  containing the monitoring information to which the signal  1  which is transmitted from the transmitting node is added at a predetermined period of time to the relay node  5   i . When a code error  7 E occurs in the above-mentioned section, the signal  2  includes an errored code which is caused by the code error  7 E. The relay node  5   i  adds the monitoring information to the signal  2  at a predetermined period of time. When the errored code which is caused by the above-mentioned code  7 E is detected in a predetermined time, the monitoring information is added thereto after a predetermined time passes. A signal  3  to which the monitoring information is added is received at a receiving node.

TECHNICAL FIELD

[0001] The present invention relates to a communicating method. Inparticular, the present invention relates to a disturbance monitoringmethod and its operation in high-speed digital communication.

BACKGROUND ART

[0002] In a communication system for relaying and transmitting a signalwhich is transmitted from a transmitting node by a relay node andreceiving it by a receiving node, there are conventional techniques formonitoring a transmission line disturbance such as a code error and atransmission line fault as follows.

[0003]FIG. 10 is a block diagram showing a conventional monitoringmethod for a communication system.

[0004] In FIG. 10, the communication system comprises a transmittingnode 4, M pieces (M is an integer) of relay node 5 ₁ to 5 _(M) (relaynodes 5 _(i−1) to 5 _(i) are shown in FIG. 10), a receiving node 9, anda transmission line. In each of the relay node 5 ₁ to 5 _(M) and thereceiving node 9, a transmission disturbance detecting section 8 isdisposed respectively.

[0005] The transmitting node 4 transmits a signal 1. The signal 1 isrelayed and transmitted by each of the relay node 5 ₁ to 5 _(M)successively, and is received by a receiving node 9.

[0006] The signal 1 contains a communication data 1 a which is convertedto a 10B code according to an 8B/10B encoding method which is publicallyknown, a 10B (bit) code 1 b instead of an errored code, and an idle code1 c which is transmitted during a period in which the communication data1 is not transmitted. The 8B/10B encoding method is disclosed inpublically known documents such as Japanese Unexamined PatentApplication, First Publication No. Sho 59-10056.

[0007] When there is an error in the communication data 1 a encoded by8B/10B encoding method, each of the relay nodes detects these errors asa code error by a transmission disturbance detecting section 8,andrewrites the errored code to the 10B code according to the 8B/10Bencoding method so as to be transmitted to the downstream thereof.Suppose a code error 7E occurs in a section 6 between relay nodes 5_(i−1) to 5 _(i), a signal 2 having the code error 7E is received at therelay node 5 _(i). The signal 2 contains an errored code 1 d which iscaused by the code error 7E.

[0008] The relay node 5 _(i) detects the errored code 1 d by thetransmission disturbance detecting section 8 and rewrites the code 1 dto a 10B code 1 b which is according to the 8B/10B encoding method andregards a signal containing the 10B code 1 b as a signal 3 so as to betransmitted downstream thereof. The signal 3 is received at a receivingnode 9 unless a code error occurs thereafter. Therefore, the 10B code 1b in the signal 3 contains an error signal due to the code error 7E.

[0009] Also, each of the relay nodes detects abnormal receipt of thesignals as a transmission line fault by the transmission disturbancedetecting section 8 and generates a signal which refers to the 8B/10Bencoding method during a period of the transmission line fault andtransmits it to the downstream thereof. Here, “downstream” indicates arecipient of transmitted information. Also, “transmit” is defined as anoccurrence of information transmission.

[0010] In the monitoring method for the above-mentioned conventionalcommunication system, it is possible to detect a transmissiondisturbance only in a section between the transmitting node and therelay node and in a section between the relay nodes. Thus, it was aproblem in that a transmission line disturbance could not be detected byobserving only the signal 3 in the receiving node.

[0011] In order to make use of the monitoring information such as a codeerror and a transmission line fault for a purpose of maintaining thecommunication system, it was necessary to collect the monitoringinformation such as a code error and a transmission line fault sent fromeach of the relay nodes via another communication system so as totransmit the monitoring information to a receiving node. However,setting up such an extra communication system increases the cost for theoverall communication system. Therefore, there was a problem in that themonitoring information such as a code error and a transmission linefault cannot be managed desirably in the conventional communicationsystem.

[0012] A first object of the present invention is to realize amonitoring method for a communication in which the transmission linedisturbance such as a code error and a transmission line fault whichoccur between the transmitting node and the receiving node can bedetected at the receiving node even if a data communication is operatedvia relay nodes.

[0013] Also, an operation of an integrated network containing acommunication system having a different communicating method from thatof a currently-used synchronous communication system was conventionallyperformed as follows.

[0014]FIG. 11 is a connecting scheme of an integrated network A1 inwhich a currently used synchronous communication system 107 and a newcommunication system 107′ having a different communicating method fromthat of the currently-used synchronous communication system 107 areconnected according to a conventional technique.

[0015] The integrated network A1 contains a synchronous communicationsystem 107, a new communication system 107′, and a communicating methodconverting node A2 for connecting the synchronous communication system107 and the new communication system 107′.

[0016] The synchronous communication system 107 contains a communicatingsection 150 for performing communication according to a synchronousframe communicating method 105 having a predetermined frame structure101 and operating a transmission and receipt of a frame signal 109containing a control information 103 having n (n is an integer) bitlength for maintaining the communication data 102 and the communicationsystem at a predetermined interval of frame time 104 in a successivemanner and a network operation section 130 which is operated accordingto a control information processing method 106 for processing thecontrol information 103 which is used to maintain the communicationsystem.

[0017] The new communication system 107′ contains a communicationsection 150′ in which a signal 109′ containing a communication data 102′and a control information 103′ having at least N (N is an integer largerthan n) bit length can be communicated according to a communicatingmethod 105′ which is different from the synchronous frame communicatingmethod 105 during a frame time 104 according to a communicating method105′ and a network operation section 130′ which is according to acontrol information processing method 106′ for performing a processingof the control information 103′ which is used for maintaining thecommunication system.

[0018] The control information processing method 106′ in the newcommunication system 107′ in the integrated network A1 is different fromthe control information processing method 106 in the currently-usedsynchronous communication system 107. Therefore, it was necessary todevelop new software for realizing the control information processingmethod 106′ for implementing the new communication system 107′.

[0019] Also, in the integrated network A1, network operation isperformed both by the control information processing method 106 for thesynchronous communication system 107 and the control informationprocessing method 106′ for the new communication system 107′.

[0020] Thus, there was a possibility that the cost of the hardware inthe integrated network A1 could be reduced by introducing the newcommunication system 107′. However, because development of a newsoftware for realizing the control information processing method 106′must accompany a cost increase, it was a problem in that the integratednetwork cannot be realized economically.

[0021] Also, there was no operation service provider who can guaranteethe quality of the signal which is transmitted by both of thesynchronous communication system 107 and the new communication system107′ between the transmitting node and the receiving node. Thus it was aproblem in that no one can provide a quality-guaranteed service.

[0022] A second object of the present invention is to provide acommunication system such that the new software for realizing thecontrol information processing method 106′ is developed by utilizing thecontrol information processing method which is adopted in thecurrently-used synchronous communication system so as to realize networkoperation in a seamless manner in the integrated network containing thecurrently used synchronous communication system and the newcommunication system.

DISCLOSURE OF INVENTION

[0023] In a first aspect of the present invention, a monitoring methodfor a communication system for relaying signals which are transmittedfrom a transmitting node by one or more relay nodes successively and thereceiving thereof by a receiving node is characterized in that:

[0024] each of the relay nodes add a first monitoring information whichindicates no disturbance or a second monitoring information whichindicates an occurrence of a transmission line disturbance to thereceived signals at a predetermined timing and transmit this to adownstream;

[0025] each of the relay nodes transmit the second monitoringinformation when the transmission line disturbance is detected betweenthe monitoring information which was transmitted previously and themonitoring information which is supposed to be transmitted; and

[0026] each of the relay nodes transmit the first monitoring informationwhen the transmission line disturbance is not detected.

[0027] By doing this, it is possible to transmit the monitoringinformation easily from each of the relay nodes periodically; therefore,it is possible to realize hardware for the relay node.

[0028] In a second aspect of the present invention, a monitoring methodfor a communication system for relaying signals which are sent from atransmitting node by one or more relay nodes successively and receivingthereof by a receiving node is characterized in that:

[0029] a transmitting node adds a monitoring information which indicatesno disturbance to a signal which is supposed to be sent at apredetermined timing and is transmitte;

[0030] each of the relay nodes stops transmitting all the monitoringinformation that are received when the each node is detecting thetransmission line defect and adds the monitoring information whichindicates the occurrence of the transmission line fault at apredetermined timing and transmits this downstream; and

[0031] each of the relay nodes replaces the monitoring information whichis received after the relay node detects the code error and indicates nodisturbance with monitoring information which indicates a code error andtransmits this downstream.

[0032] By utilizing such features, each node rewrites the monitoringinformation which is sent from upstream, or transmits substituteinformation instead of transmitting it downstream. By doing this, thetransmitted amount of the monitoring information is maintained at aconstant level even if the number of relay nodes increases. By applyingthe present invention to a communication system in which there is alimit on the amount of transmitting monitoring information, it ispossible to realize a flexible communication system which does not needto limit the number of the relay nodes.

[0033] In a third aspect of the present invention, a communicatingmethod for a communication system which uses a synchronous framecommunicating method as a first communication method for communicating aframe signal having a communication data and a first control informationhaving n (n is an integer) bit length and a predetermined framestructure in a predetermined frame time interval and a controlinformation processing method for processing the first controlinformation is characterized in that:

[0034] a signal having the communication data and a second controlinformation having N (>n) bit length is communicated by using the secondcommunicating method which is different from the first communicatingmethod in the predetermined frame time interval; and

[0035] the second control information containing the first controlinformation is communicated in the predetermined frame time interval.

[0036] By using such a communicating method, a control information whichis necessary for a control information processing method in thecurrently used synchronous communication system transmitted by a virtualframe which is equivalent to a frame of the currently used synchronouscommunication system. Therefore, it is possible to employ the controlinformation processing method in the currently used synchronouscommunication system without modification.

[0037] Furthermore, in such an integrated network in which a currentlyused synchronous communication system and a communication system towhich the communicating method according to the present invention isapplied are combined, it is possible to unify the control informationprocessing method. Therefore, it is possible to operate an integratednetwork as smoothly as the operation of the network system whichcontains only currently used synchronous communication system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0038]FIG. 1 is a block diagram of a monitoring method for acommunication system according to a first embodiment of the presentinvention in which a code error occurs.

[0039]FIG. 2 is a timing chart showing an operation of a communicationsystem to a code error by a monitoring method according to a firstembodiment of the present invention monitoring method.

[0040]FIG. 3 is a block diagram of a monitoring method for acommunication system according to a second embodiment of the presentinvention in which a code error occurs.

[0041]FIG. 4 is a timing chart showing an operation of a communicationsystem to a code error by a monitoring method according to a secondembodiment of the present invention monitoring method.

[0042]FIG. 5 is a block diagram of a monitoring method for acommunication system according to a second embodiment of the presentinvention in which a transmission line fault occurs.

[0043]FIG. 6 is a timing chart showing an operation of a communicationsystem to a transmission line fault by a monitoring method according toa second embodiment of the present invention monitoring method.

[0044]FIG. 7 is a block diagram showing an integrated network accordingto a third embodiment of the present invention.

[0045]FIG. 8A and 8B are views showing signals and frame structure ofthe synchronous communication system 107 employing Synchronous DigitalHierarchy (hereinafter called SDH) method as shown in FIG. 7.

[0046]FIG. 9 is a timing chart showing an example of signals handled ina new communication system 107′.

[0047]FIG. 10 is a block diagram showing a monitoring method which isemployed in a conventional communication system.

[0048]FIG. 11 is a block diagram showing a structure of a conventionalintegrated network.

BEST MODE FOR CARRYING OUT THE INVENTION

[0049] Embodiments according to the present invention are explained withreference to drawings as follows.

[0050]FIG. 1 is a block diagram showing a monitoring method which isemployed in a communication system according to a first embodiment ofthe present invention. Hereinafter, the same reference numerals areapplied to corresponding members as shown in FIG. 10 so as to omit therepeated explanation thereof.

[0051] In FIG. 1, each of the relay node 5 ₁ to 5 _(M) is provided witha monitoring information transmitting section 10 and a timer 11. Also, areceiving node 9 is provided with a monitoring information receivingsection 12. An operation in which a signal 1 which is transmitted from atransmitting node 4 is relayed by relay node 5 ₁ to 5 _(M) untilreceived at a receiving node 9 is the same as an operation shown in FIG.10.

[0052] In the present embodiment, as shown in FIG. 2, each of the relaynodes adds a monitoring information such as no disturbance notificationmonitoring information 2S or a code error notification monitoringinformation 2E which are transmitted from the monitoring informationtransmitting section 10 to a received signal at every period of time T1which is kept by a timer 11 so as to transmit it downstream. The nodisturbance notification monitoring information 2S and the code errornotification monitoring information 2E are generated by replacing aportion of an idle code 1 c as shown in the drawing.

[0053] Next, an operation in a case in which a code error 7E occurs in asection 6 between relay node 5 ₁ to 5 _(M) shown in FIG. 1 is explainedwith reference to FIG. 2.

[0054] The relay nodes 5 _(i−1) transmit a signal 2 containing a signal1 which is received from a transmitting node 4 to which a no disturbancenotification monitoring information 2S_(i−1) is added at every period oftime T1 to a relay node 5 _(i). Accordingly, when a code error 7E occursin the section 6, the signal 2 contains an erroneous code 1 d caused bythe code error 7E.

[0055] A relay node 5 _(i) adds a no disturbance notification monitoringinformation 2S_(i) to the received signal 2 at every period of time T1.When an erroneous code 1 d is detected during the time T1, the relaynode 5 _(i) adds the code error notification monitoring information2E_(i) after the time T1 passes. The signal to which the no disturbancenotification monitoring information 2S_(i) and the code errornotification monitoring information 2E_(i) are added becomes a signal 3so as to be received at the receiving node 9. Therefore, the monitoringinformation which is transmitted from the relay node 5 _(i) contains acondition of a transmission line disturbance which is detected by therelay node 5 _(i) between the previous transmission and the currentlyoperated transmission.

[0056] Here, each of the relay nodes relays the monitoring informationwhich is received upstream to downstream without change.

[0057] Accordingly, the receiving node 9 detects the no disturbancenotification monitoring information 2S, code error notificationmonitoring information 2E, and the 10B code 1 b in the received signal 3by using the monitoring information receiving section 12 andinvestigates a relationship of the above-mentioned information and codeso as to determine a condition of code error in the transmission line.

[0058] Also, when a transmission line fault occurs in the section 6, therelay node 5 _(i) transmits a transmission line fault notificationmonitoring information 2D (not shown in the drawing) which indicates atransmission line fault to the downstream during a period oftransmission line fault at every period of time T1.

[0059] Accordingly, the receiving node 9 detects the transmission linefault notification monitoring information 2D in the received signal 3 byusing the monitoring information receiving section 12 and investigates arelationship of the above-mentioned information so as to determine acondition of transmission line fault in the transmission line.

[0060] According to the present embodiment, it is possible to determinea condition of the transmission line disturbance such as code error andtransmission line fault in a transmission line between the transmittingnode 4 and the receiving node 9.

[0061] Also, the present embodiment requires only that a function fortransmitting a monitoring information which indicates a transmissionline disturbance which is detected at the relay node to downstreamperiodically be added to the relay node. Therefore, it is possible tosimplify the hardware of the relay node.

[0062]FIG. 3 is a block diagram of a communication system employing amonitoring method according to a second embodiment of the presentinvention. Hereinafter, the same reference numerals are applied tocorresponding members as shown in FIGS. 1 and 10 so as to omit therepeated explanation thereof.

[0063] In the present embodiment, a monitoring information transmittingsection 10 and a timer 11 are provided to a transmitting node 4.

[0064] The transmitting node 4 transmits the no disturbance notificationmonitoring information 2S of which idle code 1 c is replaced todownstream regularly at every period of time T1.

[0065] Next, an operation in a case in which a code error 7E occurs in asection 6 between relay nodes 5 _(i−1) to 5 _(i) shown in FIG. 3 isexplained with reference to FIG. 4.

[0066] When a relay node 5 _(i) detects a 10B code 1 d caused by a codeerror in a no disturbance notification monitoring information 2S in asignal 2 which is sent from a relay node 5 _(i−1) in a measuring timeT1, the relay node 5 _(i) replaces the no disturbance notificationmonitoring information 2S by a code error notification monitoringinformation 2E_(i) after the time T1 passes, and transmits the codeerror notification monitoring information 2E_(i) as a signal 3 todownstream. In addition, each of the relay nodes can relay the codeerror notification monitoring information 2E which is transmitted by arelay node which is disposed upstream.

[0067] Next, an operation in a case in which a transmission linedisturbance 7D occurs in a section 6 between relay nodes 5 _(i−1) to 5_(i) shown in FIG. 5 is explained with reference to FIG. 6.

[0068] When the relay node 5 _(i) detects the transmission linedisturbance 7D in the signal 2, the relay node 5 _(i) stops relaying allthe monitoring information which are transmitted from upstream duringthe detecting time T1 and transmits a transmission line faultnotification monitoring information 2Di which indicates an occurrence ofa transmission line fault at every period of time T1.

[0069] According to the present embodiment, it is possible to determinea condition of the code error and transmission line fault byinvestigating the signal 3 as shown in FIG. 4 and the signal 3 as shownin FIG. 6 in the receiving node 9.

[0070] According to the present embodiment, even if the number of therelay node increases, the transmitted amount of the monitoringinformation can be maintained at a constant level. Therefore, it ispossible to realize a flexible communication system which does not haveto limit the number of relay nodes instead of the communication systemhaving a limit to the transmitted amount of the monitoring information.

[0071] In addition, in the first and the second embodiments, the codeerror notification monitoring information 2E can contain not onlyinformation indicating whether or not the code error occurs but alsoinformation such as the number of the code error which occurred duringthe previous transmission of the monitoring information and the currenttransmission of the monitoring information; therefore, it is possible toenhance the monitoring accuracy.

[0072] Also, by giving a number to each of the relay nodes andtransmitting monitoring information containing information such ascondition of the transmission line disturbance and information such asthe number of the relay node which detects the disturbance, it ispossible to specify which section a disturbance occurred at in thereceiving node.

[0073] The present invention can be applied not only to a communicationsystem having only one stage such a transmitting node and a receivingnode but also to each stage in a communication system having multi-stagestructure concurrently. For example, the present invention is applied toa communication system having a stage 1 and a stage 2, it is possiblenot only to monitor a transmission line disturbance which occurs in asection between the transmitting node and the receiving node in thestage 1 but also to monitor a transmission line disturbance which occursin a section between the transmitting node and the receiving node in thestage 2.

[0074] As explained above, according to the present invention, it ispossible to transmit information about an occurrence of a transmissionline disturbance such as a code error and a transmission line faultwhich is detected at each relay node to the receiving node without anextra communication system in order to monitor a transmission linedisturbance such as a code error and a transmission line fault for thepurpose of maintaining the communication system in which a signal whichindicates a code error and a transmission line fault which occur duringthe data transmission due to the existence of the relay node does notreach the receiving node.

[0075] As explained above, in the present invention, it is possible toprovide a monitoring method for transmitting a monitoring informationsuch as transmission line disturbance which occurs in a section betweenthe transmitting node and the receiving node to the receiving nodeeconomically even via relay nodes.

[0076] Next, a third embodiment according to the present invention isexplained as follows. In the third embodiment, the same frame structureas the fame of the currently-used synchronous communication system isvirtually realized by unifying the control information and synchronizingthe transmission speed of the control information in a communicatingmethod which is different from the currently-used synchronouscommunication system. Under such conditions, it is possible to transmitand receive overhead information of the synchronous communication systemusing the frame at a frame frequency (virtual frame). By doing this, itis possible to realize a communication system having no difference froma operational point of view.

[0077]FIG. 7 is a block diagram showing an integrated network A1containing a currently-used synchronous communication system 107 and anew communication system 107′ having a new protocol different from thatof the synchronous communication system 107.

[0078] The integrated network A1 contains the synchronous communicationsystem 107, the new communication system 107′, and a communicationmethod converting node A2 for connecting the above-mentioned systems.

[0079] Also, network operation sections 100 are provided to thesynchronous communication system 107 and the new communication system107′ respectively. The network operation sections 100 processes thecontrol information 103 and the control information 103′ according tothe control information processing method 106 which refers to an SDHframe overhead processing method which is mentioned later.

[0080] The synchronous communication system 107 transmits and receivesthe control information which is used for the purpose of maintenance ofthe communication data 102 and the communication system by using acommunicating section 150 according to a synchronous frame communicatingmethod 105 having an SDH frame.

[0081]FIG. 8A shows a signal which is handled by a synchronous framecommunicating method 105. FIG. 8B shows a frame structure in thesynchronous frame communicating method 105.

[0082] As shown in FIG. 8A, in the synchronous frame communicatingmethod 105, the communication data 102 and the control information 103are transmitted and received with an interval of frame time 104 such as125 μs continuously by using a frame having frame structure 101 whichrefers to the SDH.

[0083] As shown in FIG. 8B, the control information 103 contains thecontrol information bytes 108-1 to 108-m (m is an integer) such as allor a portion of each byte of a regenerator section overhead, each byteof a multiplex section overhead, and a higher order path overhead. Thecontrol information processing method 106 performs a processing to thecontrol information 103 which is used for the purpose of themaintenance. Also the control information processing method 106 refersto the SDH frame overhead processing method.

[0084]FIG. 9 is an example of a timing chart showing a signal which ishandled in the new communication system 107′.

[0085] The new communication system 107′ transmits and receives thecommunication data 102′ and the control information 103′ such as mpieces of control information block 108-1′ to 108-m′ containing K (K isan integer) pieces of code per one block during 125 μs of frame time 104according to a communication method 105′ which is different from thesynchronous frame communicating method 105 by using the communicatingsection 150′. The control information block 108B-i′ (i is an integerfrom 1 to m) contains a code which indicates the control informationbyte 108-i′ which is equivalent to the control information byte 108-i.Also, each block contains control information identification bits C1 andC2 containing one or a plurality of bit for specifying theidentification of the control information byte which is included in eachblock.

[0086] For a transmission of the control information block 108B-i′, thetransmission of m pieces of control information block 108B-1′ to 108B-m′is completed the frame time 104 (125 μs) while the communication data102′ is not transmitted. After that, frame timing is generated at 125μs, and the transmission starts from the control information block108B-1′ according to the above-mentioned timing. The transmission of thecontrol information block which is equivalent to a next frame does notstart during a period which is after the completion of the transmissionof the control information block 108B-m′ and before the next frametiming.

[0087] In the receipt of the control information block 108B-i′, when thecontrol information block containing a control informationidentification bit which indicates the control information block 108B-i′is detected, a frame timing is restored by removing a jitter componentfrom the detected timing.

[0088] Also, when the control information identification bit in thereceived control information block indicates a control information byte108-i′, the control information byte 108-i′ is obtained from the block.Among the control information block 108B-2′ to 108B-m′ which aresupposed to be received, when a control information block 108B-j′ is notreceived, it is determined that a code error occurs in the controlinformation byte 108-j′ during transmission; thus, a predetermined errorprocessing is performed.

[0089] For a control information processing method for the controlinformation byte 108-i′ which is used for the purpose of maintaining thenew communication system 107′, the control information processing method106 which is used in the synchronous communication system 107 isemployed.

[0090] As explained above, in the new communication system 107′ to whichthe communicating method according to the present invention is applied,the control information in the currently-used synchronous communicationsystem 107 is unified, and the transmission speed of the controlinformation is synchronous. Therefore, it is possible to realize avirtual frame which is equivalent to a frame in the currently-usedsynchronous communication system.

[0091] By doing this, it is possible to employ the control informationprocessing method 106 in the currently-used synchronous communicationsystem 107 to the new communication system 107′ to which a communicatingmethod according to the present invention is applied without change.

[0092] Also, in the integrated network in which the currently-usedsynchronous communication system 107 and the new communication system107′ to which the communicating method according to the presentinvention is applied are unified, it is possible to have a unifiedcontrol information processing method 106. Thus, it is possible torealize an operation of the integrated network which is equivalent to acase in which only the currently used synchronous communication system107 is used.

[0093] Also, the present embodiment is preferable for a packetcommunication such as on an Ethernet.

[0094] Here, in a transmission of the control information 103′ in thenew communication system 107′, among m pieces of the control informationblocks 108B-1′ to 108B-M′, it is possible not to transmit a controlinformation block 108B-i which coincides a default value. In such acase, when the control information 103′ is received, it is determinedthat the control information block 108B-i′ was not received at apredetermined time. When the receipt of the control information 103′ isdetected, the processing is performed similar to the case in which thecontrol information block 108B-i′ which coincides with the default valueis received.

[0095] Also, the present invention can be applied not only to thecurrently-used synchronous communication system 107 such as SDH but alsoto other communication system in which synchronous communication isperformed using a synchronous optical network (hereinafter called SONET)or other frames.

[0096] Next, an example of a wide area network (hereinafter called WAN)to which the present invention is applied as a Giga bit Ethernet or a 10Giga bit Ethernet is explained as follows. In the following example, amaintenance monitoring information is embedded in an inter-packet gap(hereinafter called IPG). Accordingly, a maintenance monitoringinformation which is compatible with SONET is introduced to the Giga bitEthernet and 10 Giga bit Ethernet.

[0097] In SONET and SDH, the maintenance monitoring information ishandled by using a control information byte which is included in anoverhead of the frame. An operation system realizes reliable maintenancemonitoring operation by using the maintenance monitoring information. Inthe above-mentioned applied technique, maintenance monitoringinformation which is compatible with SONET is introduced to the Giga bitEthernet and 10 Giga bit Ethernet; thus, a virtual SONET is realized.

[0098] In the above-mentioned virtual SONET, information which isequivalent to an overhead of the SONET is communicated with 125 μs offrame frequency. A transmitting section replaces at least a portion ofidle which is transmitted during the IPG period by the controlinformation block (hereinafter called a virtual SONET order set)containing four codes which are defined for the use in the virtualSONET. Basically, the virtual SONET ordered set and the SONET controlinformation byte correspond in one-by-one relationship and containcontrol information which are equivalent to an ID (identificationinformation) of the SONET control information and SONET controlinformation byte. Here, a virtual SONET ordered set which corresponds tothe SONET control information byte (synchronizing byte, pointer byte,etc.) which is not necessary for the Gigabit Ethernet and 10 GigabitEthernet is not defined. A receiving section receives the virtual SONETordered set and reads the contained control information. The samebandwidth as that in the SONET overhead is obtained by transmitting thevirtual SONET order set which corresponds to the SONET controlinformation byte which is supposed to be transmitted in the 125 μs whichis the same as the SONET frame frequency. A virtual SONET order setwhich indicates a frame per every 125 μs is defined as |r|. The |r| istransmitted within 14 μs from the frame boundary timing.

[0099] Next, an example of code combination of the virtual SONET orderset is shown as follows. Various code combination can be proposed, andone example is a virtual SONET order set which contains four codes suchas [Og: d1: d2: b]. Here, “Og” in the top of the combination is aspecific code which indicates a virtual SONET ordered set. The “d1” isan ID which relates to a domain such as section, line, or a path. “d2”is also an ID which relates to functions such as an alarm, trace, andparity. The “b” is a control information which is equivalent to theSONET control information byte. For the |r| which indicates an order setindicating the above-mentioned frame boundary, order sets containing“d1” and “d2” which are zero are allocated.

[0100] The control information byte is fixed in the SONET frame. Incontrast, the location of the above-mentioned virtual SONET order set(not including “|r|”) is flexible in a virtual frame which is indicatedby the frame boundary order set |r|.

[0101] By the above-mentioned application of the present invention, itis possible to manage the Gigabit Ethernet and 10 Gigabit Ethernet by anoperation system which is operated by SONET and SDH in an integralmanner.

[0102] By doing this, the following advantages are obtained in thepresent invention.

[0103] 1). It is not necessary to develop a new operating system.

[0104] 2). It is easy to introduce a reliable monitoring function for aSONET and SDH.

[0105] 3). The monitoring function fits the WDM and SONET.

[0106] As shown above, the present invention has superior effects suchas reducing the cost for developing a new operating system by utilizinga control information processing method without change which is employedin the currently used synchronous communication system and a seamlessnetwork operation in the integrated network containing the currentlyused synchronous communication system.

1. A monitoring method for a communication system for relaying signalswhich are transmitted from a transmitting node by one or more relaynodes successively and receiving thereof by a receiving node, wherein:each of the relay nodes add a first monitoring information whichindicates no disturbance or a second monitoring information whichindicates an occurrence of a transmission line disturbance to thereceived signals at a predetermined timing and transmits themdownstream; each of the relay nodes transmit the second monitoringinformation when the transmission line disturbance is detected betweenthe monitoring information which was transmitted previously and themonitoring information which is supposed to be transmitted; and each ofthe relay nodes transmit the first monitoring information when thetransmission line disturbance is not detected.
 2. A monitoring methodfor a communication system according to claim 1 wherein the transmissionline disturbance is a code error and/or a transmission line fault.
 3. Amonitoring method for a communication system according to claim 1wherein the monitoring information which indicates the code errorindicates whether or not the code error occurs and is represented by thenumber of code error occurring between the previous transmission of themonitoring information and the present transmission.
 4. A monitoringmethod for a communication system according to claim 1 wherein themonitoring information contains a condition of the transmission linedisturbance and a relay node number which is given to each of the relaynodes.
 5. A monitoring method for a communication system for relayingsignals which are sent from a transmitting node by one or more relaynodes successively and receiving thereof by a receiving node, wherein: atransmitting node adds a monitoring information which indicates nodisturbance to a signal which is supposed to be sent at a predeterminedtiming and transmits it; each of the relay nodes stops transmitting allthe monitoring information that are received while the each node isdetecting the transmission line defect and adds the monitoringinformation which indicates the occurrence of the transmission linefault at a predetermined timing and transmits it downstream; and each ofthe relay nodes replaces the monitoring information which is receivedafter the relay node detects the code error and indicates no disturbancewith a monitoring information which indicates a code error and transmitsit the downstream.
 6. A monitoring method for a communication systemaccording to claim 5 wherein the monitoring information which indicatesthe code error indicates whether or not a code error occurs and isrepresented by the number of the code error occurring between theprevious transmission of the monitoring information and the presenttransmission.
 7. A monitoring method for a communication systemaccording to claim 5 wherein the monitoring information contains acondition of the transmission line disturbance and a relay node numberwhich is given to each of the relay nodes.
 8. A relay node apparatus fora communication system for relaying signals which are sent from atransmitting node by one or more relay nodes successively and receivingit by a receiving node, wherein: a first monitoring information whichindicates no disturbance or a second monitoring information whichindicates an occurrence of a transmission line disturbance is added tothe signals which are received from an upstream at a predeterminedtiming and transmit it a downstream; the second monitoring informationis transmitted when the transmission line disturbance is detectedbetween the monitoring information which was transmitted previously andthe monitoring information which is supposed to be transmitted; and thefirst monitoring information is transmitted when the transmission linedisturbance is not detected.
 9. A relay node apparatus for acommunication system for relaying signals which are sent from atransmitting node by one or more relay node apparatuses successively andreceiving thereof by a receiving node apparatus, wherein: the relay nodeapparatus stops transmitting all the monitoring information that arereceived from the nodes disposed upstream thereof during the relay nodeapparatus is detecting the transmission line fault and adds themonitoring information which indicates the occurrence of thetransmission line fault at a predetermined timing and transmits itdownstream; and each of the relay nodes replaces the monitoringinformation which is received after the relay node detects the codeerror and indicates no disturbance with a monitoring information whichindicates a code error and transmits it downstream.
 10. A communicationsystem for relaying signals which are transmitted from a transmittingnode apparatus by one or more relay node apparatuses successively andreceiving it by a receiving node apparatus, wherein: the transmittingnode apparatus adds a monitoring information such as a first monitoringinformation which indicates no disturbance or a second monitoringinformation which indicates an occurrence of a transmission linedisturbance to a signal which is received from the nodes disposedupstream thereof at a predetermined timing and transmits it downstream;each of the relay node apparatuses transmit the second monitoringinformation when the transmission line disturbance is detected betweenthe monitoring information which was transmitted previously and themonitoring information which is supposed to be transmitted; and each ofthe relay node apparatuses transmit the first monitoring informationwhen the transmission line disturbance is not detected.
 11. Acommunication system for relaying signals which are transmitted from atransmitting node apparatus by one or more relay node apparatusessuccessively and receiving thereof by a receiving node apparatus,wherein: the transmitting node apparatus adds a monitoring informationwhich indicates no disturbance to a signal which is supposed to betransmitted at a predetermined timing and transmits it; the relay nodeapparatus stops transmitting all the monitoring information that arereceived during the relay node apparatus is detecting the transmissionline fault and adds the monitoring information which indicates theoccurrence of the transmission line fault at a predetermined timing andtransmits it; and each of the relay nodes replaces the monitoringinformation which is received after the relay node detects the codeerror and indicates no disturbance with a monitoring information whichindicates a code error and transmits it downstream.
 12. A communicatingmethod for a communication system which uses a synchronous framecommunicating method as a first communication method for communicating aframe signal having a communication data and a first control informationhaving n (n is an integer) bit length and a predetermined framestructure in a predetermined frame time interval and a controlinformation processing method for processing the first controlinformation, wherein a signal having the communication data and a secondcontrol information having N (>n) bit length is communicated by usingthe second communicating method which is different from the firstcommunicating method in the predetermined frame time interval; and thesecond control information containing the first control information iscommunicated in the predetermined frame time interval.
 13. Acommunicating method according to claim 12 wherein; the firstcommunicating method uses an SDH frame; the control informationprocessing method refers to an overhead processing method for the SDHframe; the predetermined frame time is 125 μs; the first controlinformation contains the control information bytes 108-1 to 108-m (m isan integer) such as all or a portion of each byte of a regeneratorsection overhead, each byte of a multiplex section head, and a higherorder path overhead; transmitting and receiving the communication dataand the second control information which may contain more informationthan the first control information in 125 μs of frame time is possibleby the second communicating method; and the second control informationcontaining the control information byte is transmitted and received in125 μs.
 14. A communicating method according to claim 12 wherein: in thesecond communicating method, the second control information contains M(M is an integer) pieces of the control information block having K (K isan integer) pieces of code; each of the control information blockcontains a control information identification bit having a predeterminednumber of bits for identifying the control information contained in theblock; and in the frame time, M pieces of the control information blockare transmitted during the term in which the communication data is nottransmitted.
 15. A communicating apparatus for a communication systemwhich uses a synchronous frame communicating method as a firstcommunication method for communicating a frame signal having acommunication data and a first control information having n (n is aninteger) bit length and a predetermined frame structure in apredetermined frame time interval and a control information processingmethod for processing the first control information, wherein a signalhaving the communication data and a second control information having N(>n) bit length is communicated by using the second communicating methodwhich is different from the first communicating method in thepredetermined frame time interval; and the second control informationcontaining the first control information is communicated in thepredetermined frame time interval.